Modern communication or data processing systems are frequently distributed across a plurality of subnetworks, e.g. what are known as local area networks (LAN), which in turn are networked via long-range or wide area networks (WAN) to larger networks. An important principle of the architecture of such distributed communication or data processing systems is what is known as the client-server principle. Server here refers to a device which provides central services in a distributed system for a plurality of service users distributed over the network, known as clients. The clients and server generally operate autonomously, i.e. a server provides its services independently of the respective client. A client can only make use of such services as are provided by an available server, whereby after using a service the client has no further influence on the processing performed by the server.
For clients to use the services provided by a server it is necessary for the server to know and be able to address the clients and the clients the server. In other words, the relevant clients have to be assigned to the server as a basis for any interaction between client and server.
In many instances, in particular in internet protocol based networks, a server is assigned to clients by manual configuration of the relevant clients or the server. Generally this entails the internet protocol addresses of the individual clients being configured in the server or the internet protocol address of the server being configured in the clients. The clients and server are thus assigned to each other at the outset. However, a manual configuration of this kind requires a considerable amount of time and effort, particularly in large networks with a large number of potential clients. Moreover, whenever there is a need to change the assignment, e.g. due to switchover to a new server or the adding of new clients, a further manual configuration is required.
Because of the large amount of time and effort required for manual configuration, automated assignment methods known as autodiscovery methods are increasingly used. One frequently used method is based on what are known as DHCP servers (DHCP: Dynamic Host Configuration Protocol) being configured so that they can supply client or server addresses on request. Such a method does, however, require suitably configured DHCP servers to be available in every subnetwork and to be coordinated across subnetworks. In this arrangement, any change in the client-server assignment requires configuration data to be updated accordingly in the DHCP servers. DHCP servers are known for example from the internet document “Request for Comments: 2131, Dynamic Host Configuration Protocol” by R. Droms, dated March 1997.